Configuring Queue Mirroring

Prerequisite

Configuring RabbitMQ Queue Mirroring

1. Log in to the RabbitMQ management UI.
2. Click the Admin tab.

   Figure 1 Admin tab page

   
   

3. (Optional) Perform this step only if you need to specify a virtual host. Otherwise, go to 4.

   In the navigation tree on the right, choose Virtual Hosts, specify Name, and click Add virtual host to create a virtual host.

   Figure 2 Creating a virtual host

   
   

4. In the navigation tree on the right, choose Policies and set policies for the virtual host.

   Figure 3 Setting virtual host policies

   
   

   Table 1 Policy elements

   Parameter	Description
   Virtual Host	Specify the virtual host. To set policies for a specific virtual host, select the virtual host created in 3 from the Virtual host drop-down list box. If no virtual host has been created, the default value / is used.
   Name	The policy name, which can be customized.
   Pattern	Regular expression that defines the pattern for matching queues.
   Apply to	Object to which the policy applies.
   Priority	A larger value indicates a higher priority.
   Definition	Definition of the mirror, which consists of ha-sync-mode, ha-mode, and ha-params. ha-sync-mode: queue synchronization mode. Options: automatic and manual. automatic: Data is automatically synchronized from the master. manual: Data is manually synchronized from the master. ha-mode: queue mirroring mode. Options: all, exactly, and nodes. all: Mirror the queue across all nodes in the cluster. exactly: Mirror the queue to a specific number (determined through ha-params) of nodes in the cluster. nodes: Mirror the queue to specific nodes (determined through ha-params). ha-params: This parameter is used in the ha-mode mode. NOTE: Mirroring queues to all nodes in a cluster may waste network and disk I/O resources. You are advised to set parameters as follows: ha-sync-mode: automatic ha-mode: exactly ha-params: n/2 + 1. n is the total number of nodes in a cluster. The value of n/2 is rounded down. For example, if the total number of nodes in a cluster is 3, set ha-params to 2 (3/2 = 1.5, 1.5 is rounded down to 1, 1 + 1 = 2). Queues will be mirrored to a master and a standby node. This configuration ensures high data availability, and avoids unnecessary resource overhead.

5. Click Add policy.

   The following figure shows a successfully added policy.

   Figure 4 Virtual host policy